When Every Step Hurts: A Young Hiker's Unexplained Hip Pain

HISTORY: A 24 year old male with 8-month history of bilateral hip pain after a hiking trip without trauma. ​ Reported deep anterior bilateral hip pain, worse with truncal flexion- and hip flexion-based activities.​ Daily cannabis for 3 years, amyl nitrate ("poppers") every few days per year, alcohol 1-2 drinks per week, prior nicotine vaping.​ Pain most severe with gait initiation, mildly improved with prolonged walking, antalgic.​ Patient was of European descent. He denied history of sickle cell disease and prior prednisone use no more than 4 burst dosing through his life. ​ PHYSICAL EXAMINATION: Hip strength 5/5 bilaterally in IR, ER and flexion​ FABER positive bilaterally.​ FADIR positive bilaterally.​ Gait evaluation was significant for external rotation at hips without forward truncal flexion. DIFFERENTIAL DIAGNOSIS: 1) Femoroacetabular Impingement 2) Syndrome​ Inflammatory Arthritis​ 3) Idiopathic Bilateral Hip OsteonecrosisTESTS AND RESULTS: Initial X-Ray of bilateral hips June 2024 was unremarkable.​ Repeat X-ray October 2024 showed bilateral femoral head osteonecrosis with mild subchondral collapse of the superior aspects of both femoral heads.​ Rheumatological workup was significant for positive anti-nuclear antibody by IFA, 1:80 homogenous pattern and 1:80 speckled pattern, and high C3 complement. ​ Hematology consultation was recommended. ​ MRI bilateral hip without contrast revealed femoral head avascular necrosis with partial collapse. FINAL WORKING DIAGNOSIS: Idiopathic Bilateral Hip Osteonecrosis TREATMENT AND OUTCOMES: Bilateral total hip arthroplasties was advised. ​ Implant longevity given his young age, was discussed, and he wished to proceed with surgery.